d
A crystal structure is composed of a unit cell, a set of atoms arranged in a particular way, which is periodically repeated in three dimensions on a lattice. The spacing between unit cells in various directions is called its lattice parameters or constants. Increasing these lattice constants will increase or widen the band-gap \(\left(E_{g}\right)\) which means more energy would be required by electrons to reach the conduction band from the valence band. Automatically \(E_{c}\) and \(E_{v}\) decreases.